present invention relates to a turning machine or a lathe. In particular, it relates to such a turning machine which has a spindle box which rotatably supports a workpiece spindle provided with a clamping device for clamping rod-shaped workpieces, a tool support which displaces transverse to the workpiece spindle axis, a workpiece guiding bushing rotatably supported in guiding bushing support so that the guiding bushing extends coaxially to the workpiece spindle axis and mounted exchangeably in the guiding bushing support, and displacement means for relative displacement of the workpiece spindle in the guiding bush in the axial direction of the workpiece spindle.
Turning machines of the above mentioned type are known in the art. One of such turning machines is disclosed for example in the German document DE-A 3,041,171. Such a turning machine serves for working of long, thin workpieces which have a tendency to bending under the action of the cutting pressure. For this purpose a guiding bushing is provided on the longitudinal carriage and supports the workpiece during the working with the tools arranged on a transverse carriage of the longitudinal carriage near its engaging point. The guiding bushing surrounds the workpiece in its unworked region. A return movement of the longitudinal carriage during the working or a repeated working of the same workpiece region is not possible in this machine, since the workpiece diameter reduced by the working can no longer be supported by the guiding bush. The guiding bushes can be exchanged for adapting to the workpiece rods with different diameters.
The European Patent Document EP-A 226,836 discloses a turning machine with a stationary spindle stock and the guiding bush movable on the longitudinal carriage for a material removing only near the spindle box, and the guiding bush is spaced from the guiding bush support. It provides for a normal turning working for short parts. Since the guiding bushing support however remains on the machine due to the fact that it simultaneously forms the tool support, the tools can not directly engage the workpiece clamping parts. The working accuracy however decreases depending on the increase in the distance between the tool cutting point from the workpiece clamping region.